ATP-sensitive K+ Channel Activators Suppress the GABAergic Inhibitory Transmission by Acting on Both Presynaptic and Postsynaptic Sites in Rat Cultured Hippocampal Neurons

Effects of ATP-sensitive K+ (KATP) channel activators on the inhibitory transmission were explored by applying the patch-clamp technique to both presynaptic and postsynaptic hippocampal neurons prepared from neonatal rats. Diazoxide (0.5 mM) and cromakalim (0.5 mM) reduced GABAergic synaptic currents to 57 and 81% of control, respectively, and reduced the currents induced by exogenously applied GABA (10 microM) to 74 and 95% of control, respectively. These results suggest that KATP channel activators suppress the GABAergic transmission partly by reducing the GABA release and partly by affecting the postsynaptic GABA response.